What is Insulfrax

[james]

According to the manufacturer:

"Insulfrax calcium-magnesium-silicate fiber is recommended for continuous use at temperatures up to 1000°C (1832°F), and exhibits improved in-vitro solubility characteristics compared to Fiberfrax refractory ceramic fibers."

As described to me, it is a super-efficient, high heat insulator, with the advantage of being water soluable -- which is good from a health and environment persective. You should use a mask when using a product such as this, but it's better than traditional woven ceramic fiber insulation. It is an extruded, heat-resistant material that is woven into a blanket. It's the zillions (that's a technical term) of small air pockets that provide the high efficiency insulation.

I always remember that there are two reasons to insulate something. First to keep heat where you want it, and second to keep it away from where you don't want it. In the case of your brick oven, you want to aggressively insulate your oven dome to keep heat where you want it -- inside the dome and the oven chamber.

If you only wanted to keep heat from eaching the enclosure, you could encase your oven in 10" of concrete. You would rarely feel the heat of the oven in the enclosure, but you would loose all of the heat of the oven in the concrete -- your oven wouldn't cook.

Here are some simulated efficiency numbers we had thermal engineer run a while ago:

I had an insulation engineer run a test, and conclude that the blanket replaces 2" of loose vermiculite. We had them run a simulation where they added 1" of insulfrax, and reduced 1" of vermiculite. 1":4", 2":3", etc. over a 24 hour 1000F exposure. The outer face tested consistently dropped by adding 1" more insulfrax and 1" less vermiculite.

1" Insulfrax Blanket 6#, 4" Vermiculite 1000F** 172F

2" Insulfrax Blanket 6#, 3" Vermiculite 1000F** 161F

3" Insulfrax Blanket 6#, 2" Vermiculite 1000F** 151F

4" Insulfrax Blanket 6#, 1" Vermiculite 1000F** 142F

5" Insulfrax Blanket 6# ******* 1000F** 135F

So, you don't have to use Insulfrax, but I think it's a good idea.

You can find it on the Forno Bravo Store at:

http://fornobravo.com/store/product....cat=248&page=2

James

[Alf]

Here in the UK there are two different brand names of ceramic thermal blankets Unifrax (1250oc) and Kaowool (1260oc) readily available. We use both brand names depending on availability for pizza and bread ovens and find both excellent products.

We recently installed a Ristorane 130 oven in Athens and had a job sourcing a good quality thermal blanket locally. Every one wanted to supply us with Rockwood type products and tried to convince us it was just the thing for our oven. It isn’t, eventually we sourced Kaowool from some furnace-building chaps.

Alf

[Fio]

I called Unifrax, the manufacturer of fiberfrax insulating board and insulfrax insulating blankets, to clarify whether the blanket will dissolve in water. It will not; the tech sheets for it state that it exhibits excellent thermal stability AFTER immersion in water or exposure to high humidity.

According to the tech at Unifrax, "soluble" means that the dust of this product will break down in the lungs, and does not pose the same threat as ceramic fiber blankets.

I was concerned about this because I wondered if it gets wet will it just melt. It won't.

[james]

Fio,
Thanks for clearing that up. The "soluable in the lungs" part is why we decided to use Insulfrax instead of the other main ceramic insulators. It costs a little more, but it's better (less bad) for you and the environment and it seems like the right thing to do.
James

[fullback66]

What is the best way to install Insulfrax to your oven. I saw some people use chicken wire. Is that the proper way of installing?\
Please help me out.
fb66

[fullback66]

What is the best way to install Insulfrax to your oven. I saw some people use chicken wire. Is that the proper way of installing?\
Please help me out.
fb66

[wlively]

That depends on how you are finishing out the exterior of your oven.

I have a full enclosure, so simply lay the blankets down. I did run one loop of steel wire to help keep the blanket in place while curing, as I had no walls up at the time. Also helped keep it in place while pouring the loosing Perlite over it.

The chicken wire is used by those who are doing the stucco igloo finish. Can't help you on that one.

[fullback66]

I would have a full enclosure also. How many layers did you put over the oven? More is always better.As the chart says above. Did you also use vermiculite over the blankets?
fb66

[fullback66]

How far does one roll get you? Is it only one layer or two etc...
fb66

[wlively]

I bought 2 rolls and layered them making sure to completely overlap all seems. One roll, 24 inches X 25ft, will cover a 42" oven dome.

My insulation layers are; perlcrete (2-3 inches on top and 1-2 inches on sides), ceramic blanket #1, ceramic blanket #2, heavy duty aluminum foil very loose with some gaps, and then filled enclosure with Harborlite (loose silicon coated perlite).

Originally Posted by fullback66

I would have a full enclosure also. How many layers did you put over the oven? More is always better.As the chart says above. Did you also use vermiculite over the blankets?
fb66